As the wireless communication technologies become mature, plenty of new information products have been developed. Various wireless communication networks have become ones of the most important routes by the public to exchange voices, text messages, data, information, video files, etc. Transmitting and receiving these electronic data, information or files carried by an electromagnetic wave in the wireless communication necessitate the antenna.
Therefore, the antenna is one of the most important components to affect the quality of the communication. Broadly reviewing all the products and technologies of the mobile communication up to now, no matter how advanced the technologies, what integrations of components and modules and what changes to the industrial designs, the design of the antenna is still one of the most important key technologies. The antenna designs with excellent performances can effectively raise the quality of the communication. A single antenna with good antenna design should be able to cover various frequency bands required in various wireless communication networks. In addition, for the availability to the portable wireless communication devices, e.g. cellular phones, personal digital assistants, etc., carried by the users, the antennas with mini sizes should be realized.
As shown in FIG. 1, a planar inverted-F antenna (PIFA) in the prior art is used for the wireless communication network. However, when this kind of antenna is used for as a multi-frequency antenna, its planar radiation portion occupy a large area, and the distance between the radiation plane and the substrate surface is related to the frequency and bandwidth of the antenna and can not be arbitrarily adjusted.
This kind of antenna requires large power to accomplish the transmission function and large space as well, and accordingly the volume occupied by this kind of antenna in the prior art can not be effectively reduced.